Brain Has a Built-in System to Keep Unwanted Memories Out

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The Brain Has a Built-in System to Keep Unwanted Memories Out, Study Finds

By Shelly Fan in SiggularityHub

We all have memories we’d rather forget. Yet too often they bubble up into our consciousness. That gaffe at work or during an interview? A faceplant after slipping on ice on a first date? An accidental reply-all to the whole family? (Cringe).

For most, a quick jab of embarrassment, anger, or fear is all we feel and it quickly dissipates. But for people with post-traumatic disorders (PTSD) or depression, unwanted memories from their trauma can seriously derail their lives.

So how is it that these memories only sometimes invade unsuspecting minds?

A new study in the Journal of Neuroscience has some answers. By scanning the brains of 24 people actively suppressing a particular memory, the team found a neural circuit that detects, inhibits, and eventually erodes intrusive memories.

A trio of brain structures makes up this alarm system. At the heart is the dACC (for “dorsal anterior cingulate cortex”), a scarf-like structure that wraps around deeper brain regions near the forehead. It acts like an intelligence agency: it monitors neural circuits for intrusive memories, and upon discovery, alerts the “executive” region of the brain. The executive then sends out an abort signal to the brain’s memory center, the hippocampus. Like an emergency stop button, this stops the hippocampus from retrieving the memory.

The entire process happens below our consciousness, suppressing unwanted memories so that they never surface to awareness.

But what happens if memories do break into our thoughts? Here, the dACC has another task. When proactive surveillance fails, the brain region increases its alert signal to the executive—think DEFCON1—probing it to further damp down activity in the hippocampus.

“Preventing unwanted memories from coming to mind is an adaptive ability of humans,” wrote the authors, led by Dr. Michael C. Anderson at the University of Cambridge and Dr. Xu Lei at Southwest University in Chongqing, China. .... '